Determinants of S. cerevisiae dynein localization and activation:: Implications for the mechanism of spindle positioning
Determinants of S. cerevisiae dynein localization and activation:: Implications for the mechanism of spindle positioning
复制标题
DOI：
10.1016/s0960-9822(03)00013-7
复制
发表时间：
2003-03-04
期刊：
影响因子：
9.2
通讯作者：
Pellman, D
中科院分区：
文献类型：
--
作者：
Sheeman, B;Carvalho, P;Pellman, D
背景：在芽殖酵母的后期，动力蛋白将有丝分裂纺锤体插入母细胞和子细胞之间的颈部。动力蛋白依赖的纺锤体定位的机制被认为涉及招募的动力蛋白的细胞皮质，然后捕获的星形微管（aMTs）。结果：我们报告的本地化水平的动力蛋白重链的本地化和动力蛋白调节器的突变的影响，其细胞内分布的特点。芽殖酵母动力蛋白显示不连续的本地化沿着aMT，与富集在纺锤体极体和aMT加结束。Bik 1 p（CLIP-170）、Bik 1 p的货物结合结构域或Pac 1 p（LIS 1）的缺失导致动力蛋白对aMT的靶向减少。相比之下，动力蛋白的第二P环结构域中的动力蛋白的损失或突变导致动力蛋白在aMT的正端上的积累。出乎意料的是，Num 1 p的损失，提出的动力蛋白皮质锚，也导致在后期aMTs.Conclusions的正端上的动力蛋白的选择性积累：我们建议，而不是首先被招募到细胞皮质，动力蛋白被传递到皮质的聚合aMTs的正端。然后动力蛋白可能经历Num 1 p依赖性激活并转移到皮质接触区域。基于类似的影响的损失Num 1 p和损失的动力蛋白本地化，我们建议，Num 1 p也可能提高动力蛋白的运动活性或持续合成能力，也许集群动力蛋白电机。
Background: During anaphase in budding yeast, dynein inserts the mitotic Spindle across the neck between mother and daughter cells. The mechanism of dynein-dependent spindle positioning is thought to involve recruitment of dynein to the cell cortex followed by capture of astral microtubules (aMTs).Results: We report the native-level localization of the dynein heavy chain and characterize the effects of mutations in dynein regulators on its intracellular distribution. Budding yeast dynein displays discontinuous localization along aMTs, with enrichment at the spindle pole body and aMT plus ends. Loss of Bik1p (CLIP-170), the cargo binding domain of Bik1p, or Pac1p(LIS1) resulted in diminished targeting of dynein to aMTs. By contrast, loss of dynactin or a mutation in the second P loop domain of dynein resulted in an accumulation of dynein on the plus ends of aMTs. Unexpectedly, loss of Num1p, a proposed dynein cortical anchor, also resulted in selective accumulation of dynein on the plus ends of anaphase aMTs.Conclusions: We propose that, rather than first being recruited to the cell cortex, dynein is delivered to the cortex on the plus ends of polymerizing aMTs. Dynein may then undergo Num1p-dependent activation and transfer to the region of cortical contact. Based on the similar effects of loss of Num1p and loss of dynactin on dynein localization, we suggest that Num1 p might also enhance dynein motor activity or processivity, perhaps by clustering dynein motors.